KR20010100084A - The improvement method of thermal stability in TMR for MRAM applications - Google Patents
The improvement method of thermal stability in TMR for MRAM applications Download PDFInfo
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- 239000010410 layer Substances 0.000 claims description 201
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- 238000007254 oxidation reaction Methods 0.000 claims description 17
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 14
- 239000001301 oxygen Substances 0.000 claims description 14
- 229910052760 oxygen Inorganic materials 0.000 claims description 14
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- 150000004767 nitrides Chemical class 0.000 claims description 6
- 230000000903 blocking effect Effects 0.000 claims description 4
- 238000001755 magnetron sputter deposition Methods 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
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- 238000010438 heat treatment Methods 0.000 abstract description 15
- 238000009792 diffusion process Methods 0.000 abstract description 6
- 230000008569 process Effects 0.000 abstract description 5
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 abstract description 2
- 238000005245 sintering Methods 0.000 abstract description 2
- 239000010408 film Substances 0.000 description 10
- 239000000463 material Substances 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- 230000008859 change Effects 0.000 description 6
- 229910003321 CoFe Inorganic materials 0.000 description 5
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 230000005641 tunneling Effects 0.000 description 4
- 229910019041 PtMn Inorganic materials 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 229910015136 FeMn Inorganic materials 0.000 description 2
- -1 IrMn Inorganic materials 0.000 description 2
- 229910003289 NiMn Inorganic materials 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- 230000005415 magnetization Effects 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
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- 239000003302 ferromagnetic material Substances 0.000 description 1
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- 229910052763 palladium Inorganic materials 0.000 description 1
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- 238000005546 reactive sputtering Methods 0.000 description 1
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Abstract
본 발명은 열적특성이 향상된 ＭＲＡＭ용 ＴＭＲ소자 및 제조방법에 관한 것으로서, 더 상세하게는 TMR구조중 피고정층인 제1강자성층에 산화층을 형성하여 반강자성층에서 발생하는 Mn확산을 차단, 다른 층으로 이동하는 것을 막아 줌으로써 TMR소자의 열적 특성을 향상시킴과 동시에 열처리를 통하여 균일한 산화층을 형성할 수 있는 것이다.The present invention relates to a TMR device for MRM with improved thermal characteristics, and more particularly, to an oxide layer formed on a first ferromagnetic layer, which is a pinned layer in a TMR structure, to block Mn diffusion occurring in an antiferromagnetic layer, and another layer. It is possible to form a uniform oxide layer through heat treatment at the same time to improve the thermal characteristics of the TMR element by preventing the movement to.
그러므로 MRAM 제조시 CMOS와의 결합을 위해 적용되는 플라즈마 향상 화학 기상증착법 및 소결 공정등의 요구조건에 적합하다.Therefore, it is suitable for the requirements of plasma enhanced chemical vapor deposition method and sintering process that are applied for the combination with CMOS in MRAM manufacturing.
Description
본 발명은 TMR소자의 열적 특성 향상에 관한 것으로서, 더 상세하게는 TMR구조중 피고정층인 제1강자성층에 적절한 산화층을 형성하여 반강자성층에서 발생하는 Mn확산을 차단하고 다른 층으로 이동하는 것을 막아 줌으로써 TMR소자의 열적 특성을 향상시키고 동시에 열처리를 통하여 균일한 산화층을 형성하는 소자 및 제조방법에 관한 것이다.The present invention relates to improving the thermal characteristics of a TMR device, and more particularly, to form a suitable oxide layer in the first ferromagnetic layer, which is a pinned layer of the TMR structure, to block Mn diffusion occurring in the antiferromagnetic layer and to move to another layer. The present invention relates to a device and a manufacturing method for improving the thermal characteristics of a TMR device by preventing it and at the same time forming a uniform oxide layer through heat treatment.
어느 종류의 자성 물질은 자기장에 놓이면 전기적 저항이 변화한다.Some kinds of magnetic materials change their electrical resistance when placed in a magnetic field.
이 현상을 자기저항 효과라 부른다.This phenomenon is called the magnetoresistance effect.
이 효과는 자기 헤드 및 자기 센서 등의 자성 물질이 자기층의 형태로 있는 자기저항 효과 소자(이하 MRAM(자기 랜덤 액세스 메모리)라 칭한다)에 이용된다.This effect is used in magnetoresistive effect elements (hereinafter referred to as MRAM (magnetic random access memory)) in which magnetic materials such as magnetic heads and magnetic sensors are in the form of magnetic layers.
그러한 MRAM들은 외부 자기장에 높은 민감도가 요구되며 높은 응답 속도를 가지고 있다.Such MRAMs require high sensitivity to external magnetic fields and have high response speeds.
자기저항(MR)막을 사용하는 자기 랜덤 액세스 메모리(MRAM)는 엘. 제이. 쉬위에 의해, Proc. INTERMAG conf. IEEE Trans.Magn. Kyoto(1972), 405페이지에 제안되었다.A magnetic random access memory (MRAM) using a magnetoresistive (MR) film is L. second. By Xue, Proc. INTERMAG conf. IEEE Trans.Magn. Kyoto (1972), proposed on page 405.
엠. 엔. 바이비치 등의 Phys. Rev. Lett. 61(198) 2472페이지에서는, 비자성막을 통해 서로 교환-결합(exchange-coupled) 자성막들로 형성된 아티피셜 격자막이 큰 MR 효과(GMR)를 보인다는 것을 기재하고 있다.M. yen. Bibeach et al. Phys. Rev. Lett. 61 (198) on page 2472 describes that an artistic lattice film formed of exchange-coupled magnetic films through a nonmagnetic film exhibits a large MR effect (GMR).
상기 GMR막용으로 사용되는 비자성막은 Cu 등으로부터 형성된 도전막이다.The nonmagnetic film used for the GMR film is a conductive film formed from Cu or the like.
비자성막으로서 Al2O3, MgO 등을 사용한 터널링 GMR막(이하 TMR소자라 칭한다)이 적극적으로 연구되었으며 이 TMR소자를 사용한 MRAM이 제안되었다.Tunneling GMR films (hereinafter referred to as TMR devices) using Al 2 O 3 , MgO, etc. as nonmagnetic films have been actively studied, and MRAMs using these TMR devices have been proposed.
도 1은 종래 교환 바이어스형 TMR 구조의 개략도를 나타낸 것이다.1 shows a schematic diagram of a conventional exchange bias type TMR structure.
도 1a의 바톰형(Bottom type) TMR 구조는 기판(10) 위에 하부에서 상부로 버퍼층(12), 반강자성층(14), 제1강자성층(16), Al-oxide층(18), 제2강자성층(20), 보호층(22)의 구조를 가진다.The bottom type TMR structure of FIG. 1A includes a buffer layer 12, an antiferromagnetic layer 14, a first ferromagnetic layer 16, an Al-oxide layer 18, and a top-to-bottom structure on a substrate 10. The ferromagnetic layer 20 and the protective layer 22 have a structure.
도 1b의 탑형 TMR 구조는 기판(10) 위에 하부에서 상부로 버퍼층(12), 제2강자성층(20), Al-oxide층(18), 제2강자성층(16), 반강자성층(14), 보호층(22)의 구조를 가진다.The top TMR structure of FIG. 1B has a buffer layer 12, a second ferromagnetic layer 20, an Al-oxide layer 18, a second ferromagnetic layer 16, and an antiferromagnetic layer 14 from bottom to top over the substrate 10. ) And a protective layer 22.
비자성 박막인 Al-oxide층(18)으로 분리된 두개의 강자성층(16,20) 중 한 강자성층(20)은 자유롭게 회전하는 반면에 다른 강자성층(16)은 반강자성층(14)에 의하여 고정되어 있다.One of the two ferromagnetic layers 16 and 20 separated by an Al-oxide layer 18, which is a nonmagnetic thin film, is free to rotate, while the other ferromagnetic layer 16 is attached to the antiferromagnetic layer 14. Is fixed.
그러므로 자기저항은 두 강자성층(16,20)의 자화가 외부 자장에 따라서 반평형 상태로 있느냐, 혹은 평형 상태로 있느냐에 따라서 달라진다.Therefore, the magnetoresistance depends on whether the magnetizations of the two ferromagnetic layers 16 and 20 are anti-equilibrium or equilibrium depending on the external magnetic field.
일반적으로 TMR소자의 자기저항 효과는 터널링에 의한 강자성층(16,20)의 배열이 반평행일 때 큰 저항을 가지며, 평행일 때 낮은 저항을 가지게 된다.In general, the magnetoresistive effect of the TMR element has a large resistance when the arrangement of the ferromagnetic layers 16 and 20 due to tunneling is antiparallel, and a low resistance when parallel.
교환바이어스형 TMR 구조의 장점은 자유층과 피구속층의 자화배열이 낮은 자기장에서도 큰 자기저항을 얻을 수 있다는 것이다.An advantage of the exchange bias type TMR structure is that a large magnetoresistance can be obtained even in a magnetic field having a low magnetization arrangement in the free layer and the bound layer.
상기 교환바이어스형 TMR소자는 반강자성층(14)과 강자성층(16,20)이 서로 접할 때 교환이방성에 의해 계면에서 교환바이어스가 발생하며, 이 교환바이어스값이 큰 것이 TMR소자 제조에 유리하고 열적특성이 우수하다고 알려져 있다.In the exchange bias type TMR device, when the antiferromagnetic layer 14 and the ferromagnetic layers 16 and 20 are in contact with each other, exchange bias is generated at the interface due to exchange anisotropy. It is known to have excellent thermal properties.
그러므로 열적특성이 향상된 즉 높은 교환자기이방성 세기(Hex)와 높은 블로킹 온도를 갖는 새로운 반강자성층(14)을 개발하기 위한 많은 연구가 이루어지고 있다.Therefore, many studies have been made to develop a new antiferromagnetic layer 14 having improved thermal properties, that is, high exchange magnetic anisotropy strength (H ex ) and high blocking temperature.
예를 들어, FeMn 반강자성층 물질은 낮은 블로킹 온도 및 부식성이 문제점으로 지적되어, 교환 자기장이 큰 IrMn, PtMn, NiMn 등이 새로운 반강자성층 물질로 제시되고 있다.For example, FeMn antiferromagnetic layer materials have been pointed out as low blocking temperatures and corrosiveness, and new antiferromagnetic layer materials such as IrMn, PtMn, and NiMn having a large exchange magnetic field have been proposed.
그러나 상기 반강자성층(14) 물질(IrMn, PtMn, NiMn)은 온도가 올라가면 결정립계를 통하여 Mn이 확산되어 피고정층, 비자성층인 Al-oxide층(18)으로 이동하여 자기저항 및 교환바이어스값이 낮아지는 문제점이 있다.However, when the antiferromagnetic layer 14 material (IrMn, PtMn, NiMn) increases in temperature, Mn diffuses through the grain boundary and moves to the Al-oxide layer 18, which is a pinned layer and a nonmagnetic layer, so that the magnetoresistance and exchange bias value are increased. There is a problem of being lowered.
또한, 상기 반강자성층(14) 물질로 NiO, α-Fe2O3등이 제시되고 있지만 NiO는 닐온도(Neel Temperature)가 낮은 문제점이 있고, α-Fe2O3는 산소(oxide)를 사용하므로 열 방출에 문제가 있어 소자의 온도가 증가하는 단점이 있다.In addition, NiO, α-Fe 2 O 3 and the like have been proposed as the anti-ferromagnetic layer 14 material, but NiO has a problem of low Neil temperature, and α-Fe 2 O 3 has oxygen (oxide). Because of the use, there is a problem in heat dissipation, which increases the temperature of the device.
또한, 상기 Al-oxide층(18)의 계면에 Fe-oxide층을 증착하여 열처리시 Fe-oxide층의 과도 산소가 Al-oxide층(18)으로 이동하고, 계면에 Fe-oxide층을 형성하여 Mn확산에 따른 제1강자성층(16)의 모멘트를 감소시키는 것을 방지할 수 있다고 되어 있으나, Al-oxide층(18)이나 Fe-oxide층이 나란히 배열되어 터널링 현상을 좌우하는 산소층의 두께 및 특성조절이 매우 어려운 문제점이 있었다.In addition, by depositing a Fe-oxide layer at the interface of the Al-oxide layer 18, the excess oxygen of the Fe-oxide layer is transferred to the Al-oxide layer 18 during the heat treatment, to form a Fe-oxide layer at the interface Although it is said that the moment of the first ferromagnetic layer 16 due to the diffusion of Mn can be prevented, the Al-oxide layer 18 or the Fe-oxide layer is arranged side by side, and the thickness of the oxygen layer affecting the tunneling phenomenon and There was a problem that the characteristics adjustment is very difficult.
본 발명은 상술한 문제점을 해결하기 위하여 안출된 것으로서, TMR 구조중피고정층인 강자성층에 적절한 산화층을 첨가하여 반강자성층에서 발생하는 Mn확산을 차단하고 다른 층으로 이동하는 것을 막아 줌으로써 TMR소자의 열적 특성을 향상시키고 동시에 열처리를 통하여 균일한 산화층을 형성할 수 있는 열적특성이 향상된 ＭＲＡＭ용 ＴＭＲ소자 및 제조방법을 제공하는데 그 목적이 있다.The present invention has been made to solve the above problems, by adding an appropriate oxide layer to the ferromagnetic layer, which is a fixed layer of the TMR structure, to block the diffusion of Mn generated in the anti-ferromagnetic layer and to prevent the transfer to another layer of the TMR device It is an object of the present invention to provide a TRM device for MRM and an improved method for improving thermal properties that can form a uniform oxide layer through heat treatment at the same time.
상술한 목적을 달성하기 위하여 본 발명은, Si기판 상부와, Si기판에 oxide나 nitride 처리한 상부에 아래에서 위로 버퍼층/반강자성층/제1강자성층/Al-oxide층/제2강자성층/보호층이 순서대로 적층되거나, 버퍼층/제2강자성층/Al-oxide층/제1강자성층/반강자성층/보호층이 순서대으로 적층되는 ＭＲＡＭ용 TMR소자에 있어서; 상기 반강자성층에 가까운 제1강자성층에는 5Å-20Å 두께의 산화층이 형성됨을 특징으로 하는 열적특성이 향상된 ＭＲＡＭ용 ＴＭＲ소자를 제공하고자 한다.In order to achieve the above object, the present invention provides a buffer layer / antiferromagnetic layer / first ferromagnetic layer / Al-oxide layer / second ferromagnetic layer / A MMR element for MAMA in which protective layers are sequentially stacked or buffer layers / second ferromagnetic layers / Al-oxide layers / first ferromagnetic layers / antiferromagnetic layers / protective layers are stacked in sequence; The first ferromagnetic layer close to the anti-ferromagnetic layer is to provide a TMR element for MRM AAM improved thermal characteristics, characterized in that the oxide layer of 5Å-20Å thickness is formed.
상술한 목적을 달성하기 위하여 본 발명은, Si기판 상부와, Si기판에 oxide나 nitride 처리한 기판 상부에 아래에서 위로 버퍼층/반강자성층/제1강자성층/Al-oxide층/제2강자성층/보호층 순이나, 버퍼층/제2강자성층/Al-oxide층/제1강자성층/반강자성층/보호층 순으로 직류 마그네트론 스퍼터링 방식으로 증착하여 적층하고, 상기 반강자성층에 가까운 제1강자성층에 자연 산화법으로 산화층을 형성함을 특징으로 하는 열적특성이 향상된 ＭＲＡＭ용 TMR소자의 제조방법을 제공하고자 한다.In order to achieve the above object, the present invention provides a buffer layer / antiferromagnetic layer / first ferromagnetic layer / Al-oxide layer / second ferromagnetic layer on top of an Si substrate and on top of an oxide or nitride-treated substrate. The first ferromagnetic layer close to the antiferromagnetic layer by depositing the protective layer, the buffer layer, the second ferromagnetic layer, the Al-oxide layer, the first ferromagnetic layer, the antiferromagnetic layer, and the protective layer in the order of DC magnetron sputtering. An object of the present invention is to provide a method of manufacturing a TMR device for MRMs with improved thermal characteristics, characterized in that an oxide layer is formed on a layer by a natural oxidation method.
도 1a 및 도 1b는 종래 바톰형 및 탑형 TMR 구조의 개략도이다.1A and 1B are schematic diagrams of conventional bottom and tower TMR structures.
도 2a 및 도 2b는 본 발명에 따른 바톰형 및 탑형 TMR 구조의 개략도이다.2A and 2B are schematic diagrams of bottom and tower TMR structures according to the present invention.
도 3은 본 발명에 따른 바톰형 TMR 소자의 열처리 온도에 따른 자기저항비의 비교 변화 그래프이다.3 is a comparative change graph of the magnetoresistance ratio according to the heat treatment temperature of the bottom-type TMR device according to the present invention.
도 4는 본 발명에 따른 바톰형 TMR 소자의 열처리 온도에 따른 교환바이어스의 비교 변화 그래프이다.4 is a comparative change graph of the exchange bias according to the heat treatment temperature of the bottom-type TMR device according to the present invention.
<도면의 주요부분에 대한 부호의 설명><Description of the symbols for the main parts of the drawings>
10 : 기판 12 : 버퍼층10 substrate 12 buffer layer
14 : 반강자성층 16 : 제1강자성층14: antiferromagnetic layer 16: first ferromagnetic layer
18 : Al-oxide층 20 : 제2강자성층18: Al-oxide layer 20: second ferromagnetic layer
22 : 보호층 30 : 산화층22: protective layer 30: oxide layer
이하 본 발명을 첨부된 도면을 참고로 하여 설명하면 다음과 같다.Hereinafter, the present invention will be described with reference to the accompanying drawings.
도 2에서 Si기판(자연적으로 oxide(nitride)처리가 있거나 혹은 인위적으로oxide(nitride)처리한 기판) 혹은 글라스 기판위에 버퍼층(12)/반강자성층(14)/제1강자성층(16)/Al-oxide층(18)/제2강자성층(20)/보호층(22) 혹은, 버퍼층(12)/제2강자성층(20)/Al-oxide층(18)/제1강자성층(16)/반강자성층(14)/보호층(22)의 바톰형 및 탑형 TMR 구조를 직류 마그네트론 스퍼터링 방식으로 증착한다.In Fig. 2, a Si substrate (naturally treated with oxide (nitride) or artificially treated with oxide (nitride)) or a buffer layer 12 / antiferromagnetic layer 14 / first ferromagnetic layer 16 / Al-oxide layer 18 / second ferromagnetic layer 20 / protective layer 22 or buffer layer 12 / second ferromagnetic layer 20 / Al-oxide layer 18 / first ferromagnetic layer 16 The bottom and top TMR structures of) / antiferromagnetic layer 14 / protective layer 22 are deposited by direct current magnetron sputtering.
본 발명은 증착도중 반강자성층(14)에 인접한 제1강자성층(16)에 산화층(30)을 형성하는 것을 특징으로 하는 열적 특성이 우수한 TMR 제조방법을 제공한다.The present invention provides a method of manufacturing TMR having excellent thermal characteristics, characterized in that the oxide layer 30 is formed in the first ferromagnetic layer 16 adjacent to the antiferromagnetic layer 14 during deposition.
상기 버퍼층(12)을 형성하는 물질은 Ta, Cu, Au, Al, Pd, Pt이고, (111) 집합조직(texture) 구조로 5-200Å 두께로 형성한다.The material for forming the buffer layer 12 is Ta, Cu, Au, Al, Pd, Pt, and is formed to have a thickness of 5-200Å with a (111) texture structure.
상기 반강자성층(14)을 형성하는 물질은 FeMn, IrMn, PtMn, PdPtMn으로 두께는 50-400Å으로 형성한다.The material forming the antiferromagnetic layer 14 is formed of FeMn, IrMn, PtMn, or PdPtMn with a thickness of 50-400 kPa.
제1강자성층(16)을 형성하는 물질은 CoFe, NiFe로 두께는 20-200Å으로 형성한다.The material for forming the first ferromagnetic layer 16 is made of CoFe, NiFe and the thickness of 20-200-.
상기 산화층(30)을 제1강자성층(16)에 형성함으로써 열적 특성을 향상시키기 위해서는 산화층(30)의 두께가 매우 얇아야 하며, 더욱 구체적으로는 두께가 20Å 이상이면 산화층(30)이 자성층을 단절시켜 자성층이 동일한 특성을 보이지 않고, 두께가 5Å 이하이면 산화층(30)이 절연층을 형성하지 못하여 단일 자성층의 특성을 나타내게 된다.In order to improve the thermal characteristics by forming the oxide layer 30 on the first ferromagnetic layer 16, the thickness of the oxide layer 30 should be very thin. More specifically, if the thickness is 20Å or more, the oxide layer 30 may form a magnetic layer. If the magnetic layers do not exhibit the same characteristics by being disconnected, and the thickness is 5 m or less, the oxide layer 30 does not form an insulating layer, thereby exhibiting the characteristics of a single magnetic layer.
그러므로 본 발명에서는 자연 산화방법을 이용하여 산화층(30)을 형성하되, 메인 챔버내에서 산화시키면 메인 챔버내의 타겟(target)이 오염되어 이후 자성층(30)의 형성시 타겟에 부착된 산화물을 제거해야 하는 공정상의 복잡한 문제가 있어 메인 챔버내에서 산화층을 형성한 후 로드-록(load-lock) 챔버로 이동하여 챔버 분위기를 산소 분위기로 바꾸면서, 1mTorr-100Torr 분압을 유지하여 1분에서 20시간동안 제1강자성층(16)의 표면을 산화시켜 산화층(30)을 형성한다.Therefore, in the present invention, the oxide layer 30 is formed by using a natural oxidation method, but when oxidized in the main chamber, the target in the main chamber is contaminated, and then, when the magnetic layer 30 is formed, the oxide attached to the target must be removed. There is a complicated problem in the process of forming an oxide layer in the main chamber and then moving to a load-lock chamber to change the chamber atmosphere to an oxygen atmosphere, maintaining a 1mTorr-100Torr partial pressure for 1 minute to 20 hours. The surface of the single ferromagnetic layer 16 is oxidized to form an oxide layer 30.
바람직하게는 산소 분압은 5-200mTorr, 5분-5시간 이내에서 하는 것이 유리하다.Preferably the oxygen partial pressure is advantageously within 5-200 mTorr, 5 minutes-5 hours.
산소 분압을 낮게 하며 산화 시간은 증가하고, 산소 분압을 높게 하며 산화 시간이 짧아진다.The oxygen partial pressure is lowered, the oxidation time is increased, the oxygen partial pressure is increased, and the oxidation time is shortened.
상기 산화층(30)의 형성은 순수 산소 분압에서도 가능하며 또한 산소와 질소의 분압 비율이 9:1에서 2:8까지, 산소와 질소의 적절한 비율로 혼합하여 산화를 하여도 무방하다.The oxide layer 30 may be formed at a pure oxygen partial pressure and may be oxidized by mixing oxygen and nitrogen at a ratio of 9: 1 to 2: 8 in an appropriate ratio of oxygen and nitrogen.
또한 상기 산화층(30)의 형성은 자연 산화법외에도 플라즈마 산화법, 반응성 스퍼터링법 등도 무방하다.In addition to the natural oxidation method, the oxide layer 30 may be formed by a plasma oxidation method, a reactive sputtering method, or the like.
산화층(30)을 형성한 후, 다시 메인 챔버로 이동하여 적층하지 않은 나머지 제1강자성층(16)과 도 2a에서는 Al-oxide층(18), 제2강자성층(20)과 보호층(22)을 형성하고, 도 2b에서는 반강자성층(14) 및 보호층(22)을 형성한다.After the oxide layer 30 is formed, the first ferromagnetic layer 16 and the Al-oxide layer 18, the second ferromagnetic layer 20, and the protective layer 22 which are not moved to the main chamber and are not stacked again in FIG. 2A are formed. ) And the antiferromagnetic layer 14 and the protective layer 22 are formed in FIG. 2B.
Al-oxide층(18)은 플라즈마 산화법 혹은 자연 산화법으로 5-25Å으로 형성한다.The Al-oxide layer 18 is formed to be 5-25 Å by plasma oxidation or natural oxidation.
제2강자성층(20)을 형성하는 물질은 NiFe, Cofe, NiFe/CoFe로 10-200Å 두께로 형성한다.The material forming the second ferromagnetic layer 20 is formed of NiFe, Cofe, NiFe / CoFe to a thickness of 10-200Å.
이때 NiFe인 경우 조성비는 Ni81Fe19(wt%)이고, CoFe인 경우 조성비는 Co90Fe10(at%)이다.In this case, the composition ratio of NiFe is Ni 81 Fe 19 (wt%), and the composition ratio of CoFe is Co 90 Fe 10 (at%).
이 조성에 한정되지 않고 연자성 특싱을 보유한 강자성체 이면 된다.It is not limited to this composition, but may be a ferromagnetic material having soft magnetic characteristics.
보호층(22)을 형성하는 물질은 Ta, Cu, oxide, nitride로 두께는 10-200Å으로 형성한다.The material for forming the protective layer 22 is made of Ta, Cu, oxide, or nitride and has a thickness of 10 to 200 mW.
상술한 바와 같이 도중에 산화층(30)이 제1강자성층(16) 중간에 삽입하여 제조된 TMR소자는, 산화층(30)의 효과가 미미하므로 증착된 소자를 진공 및 자장이 함께하는 열처리로를 사용하여 블로킹 온도 이상에서 열처리를 실시함으로써 균일한 산화층(30)을 형성할 수 있다.As described above, the TMR device manufactured by inserting the oxide layer 30 in the middle of the first ferromagnetic layer 16 in the middle has a slight effect of the oxide layer 30. By performing heat treatment at or above the blocking temperature, a uniform oxide layer 30 can be formed.
열처리 전의 산화층(30)은 계면이 균일하지 않지만, 50-450℃ 온도의 열처리에 의해 균일하게 생성된 산화층(30)은 소자 제조시 발생하는 열에 의한 반강자성층(14)의 확산을 막아주는 역할을 하는 것이다.Although the oxide layer 30 before the heat treatment has a non-uniform interface, the oxide layer 30 uniformly generated by the heat treatment at a temperature of 50-450 ° C. prevents the diffusion of the antiferromagnetic layer 14 due to heat generated during device manufacturing. To do.
이하 본 발명을 실시예에서 구체적으로 실시한다.Hereinafter, the present invention is specifically carried out in the Examples.
제1실시예는 Si기판(자연적으로 oxide(nitride) 처리가 있거나 혹은 인위적으로 oxide(nitride) 처리한 기판) 혹은 글라스 기판 위에, 버퍼층(12), 반강자성층(14), 제1강자성층(16), Al-oxide층(18), 제2강자성층(20), 보호층(22)의 바톰형 TMR 구조를 직류 마그네트론 스퍼터링 방식으로 증착한다.In a first embodiment, a buffer layer 12, an antiferromagnetic layer 14, and a first ferromagnetic layer 16), a bottom TMR structure of the Al-oxide layer 18, the second ferromagnetic layer 20, and the protective layer 22 is deposited by direct current magnetron sputtering.
메인 챔버의 베이스 압력(base pressure)은 2x10-8이하를 유지하여 메인 챔버의 분위기를 최대한 청정하게 하고 시료 내에 불순물의 혼입을 억제한다.The base pressure of the main chamber is maintained at 2 × 10 −8 or less to make the atmosphere of the main chamber as clean as possible and to suppress the incorporation of impurities into the sample.
증착 조건은 스퍼터링 분압은 1-2mTorr, 스퍼터링 전력은 20-100W로 하며 증착속도는 0.5-2Å/sec로 유지한다.The deposition conditions were sputtering partial pressure of 1-2mTorr, sputtering power of 20-100W and deposition rate of 0.5-2Å / sec.
상기 Al-oxide층(18)은 메인 챔버 내에 있는 타겟의 산화를 방지하기 위하여 메인 챔버에서 실시하지 않고 로드-록 챔버에서 산소분압 1-20mTorr, 산화시간 1-60초동안 플라즈마 산화를 실시하여 형성하거나, 1-500mTorr, 산화시간 1분-10시간 자연 산화를 실시하여 형성한다.The Al-oxide layer 18 is formed by performing plasma oxidation for 1-20 mTorr of oxygen partial pressure and oxidation time of 1-60 seconds in the load-lock chamber without performing in the main chamber to prevent oxidation of the target in the main chamber. Or 1-500 mTorr, oxidation time 1 min-10 hours, and natural oxidation.
그후 시료를 다시 메인 챔버로 이동후 나머지 층을 증착한다.The sample is then moved back to the main chamber and the remaining layers are deposited.
반강자성층(14)에 인접한 제1강자성층(16) 사이에 산화층(30)을 형성하기 위하여 제1강자성층(16) 두께의 반에 해당하는 만큼 먼저 제1강자성층(16)을 형성하고 이후 상기 Al-oxide층(18)의 제조와 마찬가지로 시료를 로드-록 챔버로 이동하여 산소분압을 1-500mTorr, 산화시간 1분-10시간 자연 산화를 실시하여 형성한다.In order to form the oxide layer 30 between the first ferromagnetic layer 16 adjacent to the antiferromagnetic layer 14, the first ferromagnetic layer 16 is first formed as much as half the thickness of the first ferromagnetic layer 16. Thereafter, as in the manufacture of the Al-oxide layer 18, the sample is moved to a load-lock chamber and formed by performing natural oxidation by 1-500 mTorr and an oxidation time of 1 minute to 10 hours.
이 시료를 가지고 미세가공(micro-fabrication) 공정을 이용하여 25x25μ㎡의 크기를 갖는 TMR소자가 제조된다.With this sample, a TMR device having a size of 25x25 mu m 2 is manufactured by using a micro-fabrication process.
이후 산화된 막의 산화층(30)의 효과를 주기 위하여 2X10-6Torr 진공중에서 자장을 인가하여 150-450℃까지 열처리를 실시한다.Thereafter, in order to give an effect of the oxide layer 30 of the oxidized film, a magnetic field is applied in a vacuum of 2 × 10 −6 Torr and heat-treated to 150-450 ° C.
상술한 열처리를 통하여 터널링 효과를 제공하는 Al-oxide층(18)의 계면을 제어할 뿐만 아니라 Mn의 확산을 제어하는 산화층(30)의 계면을 동시에 제어하여 자기저항비의 증가 및 열적 특성의 향상에도 기여할 수 있다.Through the above heat treatment, not only the interface of the Al-oxide layer 18 providing the tunneling effect but also the interface of the oxide layer 30 controlling the diffusion of Mn are simultaneously increased to increase the magnetoresistance ratio and improve the thermal characteristics. Can also contribute.
상온에서 소자 측정에 적합한 PCB를 제조하여 열처리한 TMR소자를 사단자 탐침법으로 R-H곡선을 측정하여 자기저항비(MR ratio)를 구한 후 열처리 온도(Annealing Temperature)에 따른 자기저항비를 나타낸 것이 도 3이다.The figure shows the magnetoresistance ratio according to the annealing temperature after measuring the RH curve by measuring the RH curve of the TMR element, which was manufactured and then heat-treated to the PCB for device measurement at room temperature. 3
도 3에서 열처리 온도가 증가함에 따라 자기저항비가 증가함을 알 수 있다.3, it can be seen that the magnetoresistance ratio increases as the heat treatment temperature increases.
제2실시예는 제1실시예와 동일한 방법으로 제조한 TMR소자를 150-450℃까지 열처리한 후 M-H곡선을 측정하여 교환바이어스 크기를 구한 것이, 도 4의 열처리 온도에 따른 교환바이어스의 크기이다.In the second embodiment, after the TMR device manufactured in the same manner as in the first embodiment is heat-treated to 150-450 ° C., the exchange bias size is obtained by measuring the MH curve, which is the size of the exchange bias according to the heat treatment temperature of FIG. 4. .
제1비교예는 Si에 SiO2을 1500Å만큼 증착한 기판(10)을 이용하여 버퍼층(12), 반강자성층(14), 제1강자성층(16), Al-oxide층(18), 제2강자성층(20), 보호층(22) TMR소자를 직류 마그네트론 방식으로 증착하여 제조하되, 각층을 버퍼층 Ta(50Å), 반강자성층 IrMn(80Å), 제1강자성층 CoFe(30Å), Al-oxide층 Al-oxide(15Å), 제2강자성층 Cofe(45Å), 버퍼층 Ta(50Å)으로하고, 제1강자성층(16)에 산화층(30)을 형성하지 않는 것을 제외하고는 제1실시예와 동일하다.The first comparative example is a buffer layer 12, the antiferromagnetic layer 14, a first ferromagnetic layer (16), Al-oxide layer 18 by using the substrate 10 is deposited by a 1500Å of SiO 2 on Si, the 2 ferromagnetic layer 20, protective layer 22 TMR elements are fabricated by direct current magnetron deposition. -Oxide layer Al-oxide (15,), second ferromagnetic layer Cofe (45Å) and buffer layer Ta (50 하고), except that the oxide layer 30 is not formed on the first ferromagnetic layer 16. Same as the example.
열처리 조건도 제1실시예와 동일하게 하여 열처리 온도에 따른 자기저항비의 변화를 나타낸 것이 도 3이다.3 shows the change of the magnetoresistance ratio according to the heat treatment temperature in the same manner as in the first embodiment.
제2비교예는 Si에 SiO2을 1500Å만큼 증착한 기판(10)을 이용하여 버퍼층(12), 반강자성층(14), 제1강자성층(16), Al-oxide층(18), 제2강자성층(20), 보호층(22) TMR소자를 직류 마그네트론 방식으로 증착하여 제조하되, 각층을 버퍼층 Ta(50Å), 반강자성층 IrMn(80Å), 제1강자성층 CoFe(30Å), Al-oxide층 Al-oxide(15Å), 제2강자성층 CoFe(45Å), 버퍼층 Ta(50Å)으로하고, 미세 가공공정을 거친후 25x25μ㎡의 크기를 갖는 TMR소자가 제조된다.Comparative Example 2 has the buffer layer 12, the antiferromagnetic layer 14, a first ferromagnetic layer (16), Al-oxide layer 18 by using the substrate 10 by an SiO 2 deposited by 1500Å on Si, the 2 ferromagnetic layer 20, protective layer 22 TMR elements are fabricated by direct current magnetron deposition; each layer is buffer layer Ta (50Å), antiferromagnetic layer IrMn (80Å), first ferromagnetic layer CoFe (30Å), Al A TMR device having a size of 25 × 25 μm with a -oxide layer Al-oxide (15Å), a second ferromagnetic layer CoFe (45Å), and a buffer layer Ta (50Å) is subjected to a fine processing process.
시료의 제조는 산화층(30)을 형성하지 않는 것을 제외하고는 제1실시예에서와 동일한 조건이 사용되고 열처리 온도에 따른 자기 바이어스의 변화를 나타낸 것이 도 4이다.4 is the same as in the first embodiment except that the sample is not formed with the oxide layer 30, and the change in the magnetic bias according to the heat treatment temperature is shown in FIG.
본 발명은 이상의 실시예에서 구체적으로 기술되었지만, 이들 실시예에 의해 한정되는 것이 아니고 특허청구범위에 기재된 기술적 사상을 벗어나지 않는 한 다양하게 변경 및 수정할 수 있음은 물론이다.Although the present invention has been described in detail in the above embodiments, it should be understood that the present invention is not limited to these embodiments and various changes and modifications may be made without departing from the technical spirit described in the claims.
이상에서 살펴본 바와 같이 본 발명에 의하면, 반강자성층에 가까운 제1강자성층에 산화층을 형성하므로 열적 특성을 대폭 향상시킬 수 있어 차세대 스핀밸브 헤드 및 자기메모리 소자에 적용될 수 있다.As described above, according to the present invention, since the oxide layer is formed in the first ferromagnetic layer close to the antiferromagnetic layer, the thermal characteristics can be greatly improved, and thus it can be applied to the next generation spin valve head and the magnetic memory device.
또한 열적특성이 향상되고 열처리에 의해 균일한 산화층이 형성되어 MRAM 제조시 CMOS와의 결합을 위해 적용되는 플라즈마 향상 화학 기상증착법 및 소결 공정등의 요구조건에 적합하다.In addition, the thermal characteristics are improved and a uniform oxide layer is formed by heat treatment, which is suitable for the requirements of plasma enhanced chemical vapor deposition and sintering process, which are applied for bonding with CMOS in MRAM fabrication.
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| KR100500455B1 (en) * | 2003-08-11 | 2005-07-18 | 삼성전자주식회사 | Magnetic tunnel junction structure having a oxidized buffer layer and method of fabricating the same |
| KR101042338B1 (en) * | 2009-10-08 | 2011-06-17 | 한국과학기술연구원 | Magnetic tunnel junction device and method for manufacturing the same |
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| KR100500455B1 (en) * | 2003-08-11 | 2005-07-18 | 삼성전자주식회사 | Magnetic tunnel junction structure having a oxidized buffer layer and method of fabricating the same |
| KR101042338B1 (en) * | 2009-10-08 | 2011-06-17 | 한국과학기술연구원 | Magnetic tunnel junction device and method for manufacturing the same |
| US8329478B2 (en) | 2009-10-08 | 2012-12-11 | Korea Institute Of Science And Technology | Magnetic tunnel junction device and method for manufacturing the same |
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